BaseAudioContext.createBufferSource()

The createBufferSource() method of the BaseAudioContext Interface is used to create a new AudioBufferSourceNode, which can be used to play audio data contained within an AudioBuffer object. AudioBuffers are created using BaseAudioContext.createBuffer or returned by BaseAudioContext.decodeAudioData when it successfully decodes an audio track.

Syntax

var source = baseAudioContext.createBufferSource();

Returns

An AudioBufferSourceNode.

Example

In this example, we create a two second buffer, fill it with white noise, and then play it via an AudioBufferSourceNode. The comments should clearly explain what is going on.

Note: You can also run the code live, or view the source.

var audioCtx = new (window.AudioContext || window.webkitAudioContext)();
var button = document.querySelector('button');
var pre = document.querySelector('pre');
var myScript = document.querySelector('script');

pre.innerHTML = myScript.innerHTML;

// Stereo
var channels = 2;
// Create an empty two second stereo buffer at the
// sample rate of the AudioContext
var frameCount = audioCtx.sampleRate * 2.0;

var myArrayBuffer = audioCtx.createBuffer(2, frameCount, audioCtx.sampleRate);

button.onclick = function() {
  // Fill the buffer with white noise;
  //just random values between -1.0 and 1.0
  for (var channel = 0; channel < channels; channel++) {
   // This gives us the actual ArrayBuffer that contains the data
   var nowBuffering = myArrayBuffer.getChannelData(channel);
   for (var i = 0; i < frameCount; i++) {
     // Math.random() is in [0; 1.0]
     // audio needs to be in [-1.0; 1.0]
     nowBuffering[i] = Math.random() * 2 - 1;
   }
  }

  // Get an AudioBufferSourceNode.
  // This is the AudioNode to use when we want to play an AudioBuffer
  var source = audioCtx.createBufferSource();
  // set the buffer in the AudioBufferSourceNode
  source.buffer = myArrayBuffer;
  // connect the AudioBufferSourceNode to the
  // destination so we can hear the sound
  source.connect(audioCtx.destination);
  // start the source playing
  source.start();
}

Specifications

Specification Status Comment
Web Audio API
The definition of 'createBufferSource()' in that specification.
Working Draft  

Browser compatibility

FeatureChromeEdgeFirefoxInternet ExplorerOperaSafari
Basic support10 webkit Yes25 No

22

15 webkit

6 webkit
FeatureAndroid webviewChrome for AndroidEdge mobileFirefox for AndroidOpera AndroidiOS SafariSamsung Internet
Basic support Yes33 Yes26 Yes No ?

See also

Document Tags and Contributors

Contributors to this page: fscholz, nylki, Jedipedia, chrisdavidmills, erikadoyle, teoli
Last updated by: fscholz,